<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #Text{
            color:blueviolet;
            font-size: large;
        }
        .txt,.title{
            color: red;
            font-size: 45px;
        }
        
    </style>
</head>
<body>
    <!--id对应#-->
    <!--class对应.-->
    <!--id名字只可使用一次-->
    <p>H</p>
    <p id="text">pbianqian</p>
    <h3>biaoti</h3>
    <p class="txt">标题23</p>
    <p class="title">标题28</p>
</body>
</html>